Parameters Analysis of Measured Lightning Overvoltages from a Substation

At present, measured overvoltages are relatively rare for the overvoltage-rated studies in power systems. The overvoltage online monitoring system developed by Chongqing University have successfully obtained thousands of valuable overvoltage data for ten years. The data mining and analysis of these measured overvoltages are very essential for understanding the statistical performance of the measured overvoltage in practical substations. Therefore, in this paper, useful signals extraction, statistics of waveform parameter are achieved. By adopting wavelet threshold de-noising method, we find that the actual lightning wave is an oscillating attenuation wave. Energy equivalent method (EEM) can convert oscillating waves into double-exponential waves. The wave front time obeys the Gaussian distribution N (24.7, 7.8
²
), and the wave tail time has greater dispersion than the wave front time. The lightning waveform with a cumulative probability of 50% is 23.5/51 μs. It provides an important guiding effect on the safe operation and protection of the substation.